Fluid pressure control mechanism



May 16, 1950 E. F. JIRSA FLUID PRESSURE CONTROL MECHANISM Fil ed Dec. 17, 1945 3 Sheets-Sheet 1 M M R s W? a W N R L O M w E A y 16, 1950 I E. F. .JIRSA 2,508,263

FLUID PRESSURE CONTROL MECHANISM Filed Dec. 17, 1943 3 Sheets-Sheet 2 A N B 5 I i l 1 l i i i as I23 s4 90 i 5: IISHTQI 80 I i i I illlfi fluy/ I I I MI/(III, V4 v 7 di l ljil I25 I k.

f J"| s 95 L-Hoo 10 1 FIG. 5

INVENTOR. EMILF. JIRSA ATTORNEYS May 16,, 1950 r E. F. JIRSA FLUID PRESSURE CONTROL MECHANISM 3 Sheets-Sheet 5 Filed Dec. 17, 1943 m QE mm M

mom

IN VEN TOR. EMIL E JIRSA Nam ATTORNEYS Figure 4 is a sectional elevational view of one of the fluid motors for shifting the gears, and drawn to an enlarged scale.

Figure 5 is a view similar to Figure 4 but shows the fluid pressure motor in a different position.

Figure 6 is a sectional elevational view taken along a line 66 in Figure 1, showing the construction of the selector valve and drawn to an enlarged scale.

Figure 7 is a front elevational view taken along a line 1-? in Figure 6.

Figure 8 is a sectional elevational view similar to Figure 7 but showing the selector valve lever set in one of its operating positions.

Figure 9 is a sectional elevational view taken along a line 9-9 in Figure 6.

Referring now to the drawings, the clutch of the vehicle is of the type which is normally biased to engaged position by means of a strong spring, as is well-known to those skilled in the art, and therefore is not shown in the drawings. The clutch is disconnected by means of a clutch throwout rod it connected at one end to the clutch and at its other end to a short arm H by means of a pivot bolt l2. The arm H is rigidly fixed to a hub l3 which is mounted on .a shaft 14 and has a bifurcated clamping section l5 which is clamped by means of a bolt IE to tightly engage the shaft l4. Akey i7 is interposed between the hub l3 and the shaft I G to prevent relative rotation therebetween.

A clutch actuating lever i8 is mounted rigidly on a hub I9, which is journaled on the shaft l4 adjacent the hub l3 and is provided with a laterally extending lug 28, which is rigidly mounted on an arm 2| extending oppositely from the operating lever l3 and rigidly fixed to the hub IS. The lug 253 extends underneath a rearwardly extending arm 22, formed integrally with the hub l3, and which is provided with a pair of adjusting bolts 23, 24 which are disposed within vertically extending threaded openings 29 in the arm 22. Bolt 23 projects downwardly beneath the arm 22 and engages a floor plate 26 to limit the movement of the shaft i 4 in a clockwise direction as viewed in Figure 1. The second bolt 24 projects downwardly beneath the arm 22 and engages the lug 20 when the latter is raised by a counterclockwise angular movement of the operating lever l8 about the axis of the shaft l4. A U-shaped spring strap member 21 is secured to the arm 22 by means of the bolts 23, 24, and is held tightly against the upper side of the arm by lock nuts 28, which also fix the adjusting bolts inadjusted position. The spring 21 curves downwardly and bears upon the top side of the lug 2|], urging the latter downwardly out of engagement with the lower end of the bolt 24. A foot pedal 25 is provided on the outer end of the lever l8, as is the usual construction of clutch operating pedals.

The shaft It is urged in a clockwise direction by the clutch spring (not shown) acting to urge the clutch operating rod If! toward the right, and thereby acting through the bolt [2 and arm I! to force the arm 22 downwardly to maintain the bolt 23 in contact with the floor plate 26. Likewise, the U-shaped spring 2'! presses downwardly on the lug 20 and thereby urges the clutch pedal arm l8 in a clockwise direction until the end of the arm 2| also engages the floor plate 26. A downward pressure upon the pedal 25 in opposition to the spring 27, moves the arm 2| upwardly until the lug 20 engages the lower end of the bolt 2 t, after which further downward pressure on the pedal 25 rotates the arm 22, hub

l3, shaft l4, and arm H, in a counterclockwise direction, thereby pulling the clutch rod Hi to the left, disconnecting the clutch against the pressure of its spring (not shown). Inasmuch as the pressure of the spring 2'! is appreciably less than the pressure of the conventional clutch spring, the first portion of the arc of movement of the operating lever I8 is accomplished with very little pressure of the operators foot upon the pedal 25, but after the lug 243 engages the bolt 24, it requires an appreciable effort on the part of the operator to continue the movement of the operating pedal against the opposition of the clutch spring.

The shaft M is rotated by a power actuated device in the form of a fluid pressure operated cylinder and piston assembly, indicated generally by reference numeral 35 and comprising a cylinder 35, within which is slidably disposed a piston 31 threaded on the end of .a piston rod 38, which is pivotally connected by a crank pin 39 to a crank 40 rigidly fixed to the shaft 14. The cylinder 36 is preferably a single casting with a closed end 4! and a supporting car 42, which is pivotally mounted by means of a pin 43 on a bracket 44, the latter being anchored on any suitable support. Hydraulic fluid, preferably oil, but which can be any suitable fluid adapted for the purpose and known to those skilled in the art, is introduced to the cylinder 36 near the head ii through a duct 45. The pressure of the fluid moves the piston 3'! toward the left in the cylinder 35, acting through the piston rod 38 and crank arm it] to rotate the shaft [4 in a counterclockwise direction. The oil is confined between the piston 31 and the cylinder head 4| by means of a cup-shaped seal 46 secured to the piston by a nut 47 on the threaded end of the piston rod 38. The piston rod 38 extendsout of the opposite end of the cylinder through a packing gland 48 disposed within a sealing cap 49 fixed to the cylinder by bolts 50, and the sealing gland 48 is maintained under compression by means of a bushing 5|.

The hydraulic fluid is supplied to the cylinder by means of a pump 55 comprising a pair of intermeshing gears 56, one of which is mounted on a drive shaft 51 connected to any suitable prime mover, such as the engine of the vehicle. The gears 58 are disposed within a casing 58, the latter being provided with a reservoir portion 59 which contains the supply of oil or other fluid.

I do not intend my invention to be limited to the use of a liquid, for compressed air or other gas may be employed for actuating the piston and cylinder assembly 35 and the other mechanism to be described herein, without departing from the spirit or scope of my invention.

The fluid fiows from the reservoir 59 to the pump through an inlet passage 60 and is carried by the gear teeth in a manner well-known to those skilled in the art and forced through a high pressure duct 6!. The flow of oil from the duct 6| to the fluid motor 35 is controlled by a valve indicated generally by reference numeral 65. The valve 55 comprises a valve casing SE, within which is disposed a high pressure chamber 6'! to which the oil flows from the duct BI and is also provided with a lower pressure chamber 68, which is connected by a return duct 69 to the reservoir 5Q. The chambers 61, 68 are interconnected by means of a valve port 10, preferably cylindrical in shape and adapted to receive a valve plunger II, the plunger ll being slidable through the port 10 for closing off the latter and preventing oil from flowing therethrough to the low pressure chamber 68. The C li der duct 45 is connected in communication with the high pressure'cham'ber B'I, butn'ormally the oil flows from' the pump 55 'throughthe duct 5 I into the high pressure chamber 61, and circulates through the normally open valve port In, the low pressurechamber 68',"and the" return duct 6 9 back to the reservoir 59; When the valve plunger II is moved into the valve port I0; closing the latter against flow of oil, the oil then flows through the cylinder duct 45 to the cylinder 36 to force the piston 31 axially within the cylinder 36, thus disconnectingthe clutch.

The Valve plunger 'II extends downwardly througha sealing gland I2 out of the valve casing 66 'and'is pivotally connected by a pin 53 to a link I4, which is pivoted at to the end of the arm ZII By proper adjustment of the bolt 24, the valve plunger II ismoved into the valveport I0 'by'th'e first portion oi the ma: travel of the clutch pedal 25, thereby causing the fluid motor 35'to disconnect the clutch by power obtained from thepump 55 as explained above, thereby relieving the operator from the necessity for further movement of the clutch pedal 25. Howeverfshould' thefiuid motor 35 fail to disconnectthe clutch for any reason, such as a lack'of pressure'due' to a break in the high pressure line BI or any other reason, the operator can'disconnect the clutch manually bycontinw ing to move the clutch pedal 25downwa'rdly until the lug engages the end of the een and the shaft I4 isthen rotated by force exerted by the operator upon the pedal 'If the pedal 25 is depressed throughout its complete range, the valve plunger 'II merely slides upwardly through the'high pressure'chamber 61 to the extreme position indicated indotte'd lines.

When the operator release's'his foot from the pedal 25, the spring 27 returns it to normal position with the end of the armZ I: in engagement with "the floor plate 26, in whichposition the valve plunger II is withdrawn from the port 10.

This releases the oil from the high pressure chamber 6'! and relieves the pressure in the cylinder 35; whereupon the pressure of the clutch spring" against 'the operating rod ID forces the piston 31 back toward'theright in'the'cy'linder and thus forcing the 'oil 'to return through the cylinder duct 45 to the 'valve casing 66, and from there through'the return duct 69'to the reservoir 59.

It will be noted that when the valve plunger II enters the port I0, the pressure of the oil within the chamber 61 is imposed 'up'on'the end of the plunger Ill and'requires a slightly increased pressure on the pedal 25 to hold the plunger in the valve port I0. 'This provides the operator with an indication that the fluid motor 35 'is operating properly, and since the'pressure on the end of the valve plunger II is proportional to the total pressure required to disconnect the clutch, the'operator, through his sense of touch,"

obtains the same sensation that hewould obtain by manual operation of the clutch, but on a smaller scale.

A duct "I6 interconnects the cylinder 36 on the low pressure side of the piston 31 with the low pressure chamber 68 in the valve casing 65. This prevents any back pressure from building up behind the piston 31. A third duct I1 is connected with the cylinder 36 at an intermediate point therein, to conduct oil from the cylinder to operate the gear shifting fluid motor after the piston 31' has traveled over substantially a complete 6 range within the cylinder 36, as will new be described.

One of the gear shift fluid motors is indicated in its entirety by reference numeral 80, the details of which are best shown in Figures 4 and 5. The fluid motor 36 comprises an outer cylinder BI having a closed head or end portion 82. The o p site end of the cylinder is closed by means of a sealing cap 83 secured by bolts 84 to the cylinder 8i. A piston rod 85 extends outwardly through the cap 33 and is sealed against oil leakage around the piston rod 85 by means of a seal ing gland 85 disposed within a recess 87 in the cap 83, and compressed therein by means of a suitable bushing 88. Slidably disposed within the cylinder 8! is an intermediate piston member 90 having a hollow interior portion 9I, which. serves as a cylinder for an inner piston 92. One end of the intermediate piston 3!! isv closed except for a cylindrical opening 93 adapted to receive the piston rod 85 slidably disposed therewithin. An annular seal 54 encircles the opening 53 and'prevents leakage of oil between the inner cylinder 9! and the outer cylinder 8|. The piston rod 85 extends through the outer and intermediate cylinders SI, and is connect d to the inner piston 92' The other end of th i t-, mediate piston 55 is closed by means of a threaded plug 95, which screws into the end of the intermediate piston 95 in oil-tight relation. A -S e Sealing m mber 8.6 i mo ted on the end of the plug 95 by means of a pairor" studs 91, there being a cup-shaped washer Sll e e e lt 91: n erv n as a um er to engage the end 82 of the cylinder ill and thus protect the cup-shaped seal 55.

Thus, it is evident that the fluid motor 811 comprisesthree telescopically arranged parts, the

cylinder 8 I, the intermediate piston 91} slidable within the cylinder BI, and the inner piston 92 slidable within the cylinder SI in the intermediate piston 95. In Figures 1 and 4 the parts are arranged in the positionsindicated for neu tral position of the fluid motor 8 9 In this pQ" sition, the intermediate piston 90 is at the left end of its stroke Within the cylinder 8I andfis in abutment with the sealing cap 83 while the inner piston 92 is at the right end of its stroke within the cylinder 9i and is in abutment with the plug 35.

vThe parts are moved to this position by introducing oil under pressure through a cylinder duct IIJIJ to the right and of thecylinder BI, thereby applying pressure to the right end of the intermediate piston 90. At the same time, the oil at the opposite endof the intermediate, piston 90 I05 connects the groove I04 with the left end of the inner cylinder QI. Oil is relieved from the right end of the inner cylinder 9 through an aperture I06 in the intermediate piston member 90, which registers with a port I01 in thecylinder 8 I, to which a duct I08 isconnected. A groove III]. extends axially toward the right in the cylinder 8I from the port I01. The grooves IM and III) insure that the cylinder ducts I02 and '"lie eg nne t d in emm n e tiqn w t the inner cylinder 9|, on opposite sides of the inner piston 92, respectively. Groove I04 and port I03 are spaced peripherally from groove I I and port I01, so that there is no communication therebetween when the parts are in the positions shown in Figure 5. The intermediate piston member 90 is prevented from rotating within the cylinder 8| by means of a stud II5 disposed in threaded engagement within a hole H6 in the cylinder SI and having an end portion I I! of reduced diameter, which projects into the cylinder BI and is slidably received Within a narrow groove I I8 extending axially along the outer surface of the intermediate piston member 90. The projection I I7 engages the groove I I8 to hold the fluid passage or groove I64 in register with the port I03 and also holds the port I06 in register with the groove IIO.

A pair of annular resilient sealing members H9, I20 are disposed in grooves which extend around the circumference of the intermediate member 90 at opposite ends of the groove I04 and prevent leakage of oil between the ports I03, I01 and the interior of the cylinder GI. Ihe in-- nor piston 02 is also provided with an annular seal I2I to prevent any flow of fluid between the piston 92 and the wall of the cylinder 9|.

In the position shown in Figure l, the fluid motor 80 is disposed in neutral position, as indicated by reference letter N in register with the groove I22 in the coupling member I23 at the" end of the connecting rod 85. Thus, in neutral position the intermediate piston 90 is at the left end of its stroke and the inner piston 92 is at the right end of its stroke. Now, to shift the coupling member I23 of the fluid motor to the operating position indicated by reference" letter B, oil under pressure is applied to the left end of the intermediate piston 90 through the cylinder duct IOI, thus forcing the intermediatepis= ton 90 toward the right until the member 98 en gages the end wall 82. At the same time, oil is maintained under pressure in the cylinder duct I02, which pressure is transmitted through the port I03, groove I04, and opening I05, to the oil within the inner cylinder SI, and hence holds the inner piston 92 rigidly against the end plug 95. Thus, there is no movement of the inner piston 92 relative to the intermediate piston 00', but both move as a unit toward the right within the outer cylinder 8| until they reach the position shown in Figure 5.

To move the fluid motor to the position indicated A from the neutral position in Figure 4, oil is supplied under pressure through the cylin' der duct I88 and flows through the port I01, groove H0 and port I08 into the inner cylinder 9| on the right hand sideof the piston 92, forc ing the latter toward the left to place the con pling member E23 in alignment with the position indicated A. While the piston 92 is moving, the oil on the opposite side of the latter is forcedoutwardly through opening I05, groove I04, port- I03, and cylinder duct I02. During this move-- ment, the intermediate piston Si? is maintained in rigid abutment against the cap 83 by main-'- taining pressure withinthe cylinder 8I on the right end of the intermediate piston 90, through the cylinder duct I08.

To return the coupling member I23 toneutral, oil is forced through cylinder duct I 02", groove I04, and opening I05 into the inner cylinder 51, while the oil from the opposite side of the piston 92 is allowed to flow outwardly through the 7 opening I06 and port I01 into duct I08, and at the same time maintaining pressure against the end of the intermediate piston 90 through the cylinder duct I00. Thus, it is evident that every movement of the fluid motor from neutral to any position, or back to neutral again, is a positive movement of parts under full oil pressure, into abutment with rigid stops. There is no possibility for the fluid motor to overshoot its mark or to stop in any indeterminate position, and when the parts reach the predetermined position, they are locked therein by full pressure of the hydraulic fluid.

When moving from one operating position A to the other operating position B, there is no necessity for the parts to stop at the neutral position N, for in this case the oil pressure is maintained on both cylinder ducts IUI, I02, thereby shifting the intermediate piston $0 to the right within the cylinder BI, and at the same time shifting the inner piston 92 to the right within the inner cylinder 91, while cylinder ducts I00, i023 are relieved to allowthe oil to flow out of the outer and inner cylinders from the right side of the pistons. Likewise, when shifting from position B to position A, oil is supplied to ducts I00 and "38 under pressure, while ducts IOI, I02 are relieved. This shifts the inner piston 92 to the left within the inner cylinder 9|, simultaneously shifts the intermediate piston 90 to the left within the cylinder 8 I.

As indicated in Figure 1, the coupling member I23 engages an ear I24 011 a shifting fork member I25, the ear I24 resting within the groove I22. The shifting fork member is regidly fixed to a shift rod I28, which is slidable axially in a manner well k'nownto those skilled in the art. The rod I26 is one of a set of three rods I26, I21, I28, in the illustrated embodiment, the number of rods and shifting fork members I25 being dependent on the design of the transmission mechanism, which is not a matter of concern in the present invention. Each of the shift rods I26, I21, I28 is provided with a separate fluid motor for driving the same, 01' one or more of the rods can be shifted by manual means while the remainder are provided with fluid motors for shifting the same. In order to simplify the present disclosure, only one of the fluid motors is shown, inasmuch as the other fluid motors are of identical design.

As indicated hereinbefore, fluid is supplied under pressure for operating the fluid motor 80, through a supply duct 'I'I, which receives oil from the clutch operating cylinder 36, after the clutch operating piston 3! has traveled over substantially a complete range within the cylinder 36. This insures that no movement of the gear shifting mechanism is made until after the clutch is disconnected, and also prevents the clutchfrom engaging during the time that the gear shifting mechanism is active in shifting the gears. The oil from the supply duct IT is distributed to the proper cylinder ducts by means of a selector valve mechanism, indicated generally by reference numeral I30, which valve also connects the proper cylinder ducts to a return conduit I3I, which conveys the return oil back to the low pressure chamber t8'of the valve 65.

The selector valve I30 comprises a valve casing I32, within which are disposed a plurality of vertically slidable valve plungers which control the flow of oil to and from the fluid motor 80', associated with the shift fork I25' and shift rod I29. The same selector valve I30 also controls the fluid motor (not shown), which is associated with the shift rod I21. One pair of valve plungers I35, I 36 control the flow in the cylinder ducts I09, IOI, I02, I08 connected with the fluid motor 80, while a second pair of valve plungers I31, I38, controls a similar set of cylinder ducts I, IOI', I02 and I08, leading to the other fluid motor (not shown).

The valve casing I32 is composed of three jzuxtaposed sections I39, I40, I4l, which are manufactured as separate parts for convenience in manufacturing, but which are rigidly bolted together by four bolts I42, which extend through aligned openings in the several sections and secure the same together to provide a single unitary casing. The supply duct 11 is connected with a port I45 in the center section I40 of the valve case. This port I45 communicates with a distributing duct I46 which extends vertically within the center casing section I40 on one side of the center line thereof. A second distributing duct I41 extends vertically through the center section I40 on the opposite side of the center line, as best shown in Figure 6. Upper and lower communicating ducts I43 extend in opposite directions from the two high pressure distributing ducts I46, I41 and connectthe latter in communication: with a plurality of high pressure compartments I49 in the outer sections I39, MI. These compartments I49. are preferably cored out of the cast casing sections l39, I41, while the passages I46, I41, I48 are drilled in the center casting I40. Thus, the compartments I49 extend inwardly from. the inner surface of the casting sections I39, MI and are closed along their inner sides by the faces of the center casting I40. Gaskets I50 are interposed between the casing sections to prevent leakage of oil therebetween.

The center casing section I40 is provided with a drilled passage I55-extending downwardly from the top of the section on the center line of the latter, the opening at the upper end of the section. being closed. by a plug I56. The passage I55 is connected by a communicating duct I51, disposed perpendicular thereto, with a pair of low pressure compartments I 50 disposed in the two outer sections I39, I 4| respectively. The chamber I58 in one of the sections I39 is connected in communication with the return duct I3I. Both of the high pressure compartments I49 and the low pressure compartment I58 in each of the casing sections I39, MI extends across the entire width of the latter and the low pressure compartment I53 is substantially midway between the vertically spaced high. pressure compartments I49. Intermediate between the low pressure compartment I 59 in each casing section and the high, pressure compartment I49 above and below the latter, are two pairs of valve compartmentsIIiIl, I60 and Nil, Nil. The pair of compartments I65, I60. are disposed in horizontal alignment with each other but are not connected together. Compartment I 69 is connected to cylinder duct I001 on the front side of the valve,,while compartment I 65" is connected with cylinder duct I 00' on, the rear side of the valve. Similarly, compartment, ISI is connected in communication with cylinder duct I !II while compartment I 6|" is connected with cylinder duct l0! on the rear, side of the valve, the compartments I6I, I6I being separate compartments but on the same horizontal level. Likewise, in valve casing section I 39,, are similar compartments I60, I60 and I6I, I6I' above'and below the low pressure compartment I58 and on the same level with the corresponding compartment in casing section MI described above, but are not connected therewith. These compartments are connected with cylinder ducts I02, I02 and I08, I08, respectively.

Each of the valve plungers I35, I36, I31 and I38 isv slidably disposed within a vertically extending cylindrical passage l65, which interconnects the several compartments I49, I59, I60, MI in the two outer valve casing sections I39, lei. Each of the valve plungers is cylindrical and fits closely'within the passage I65 but slidable therein, preventing oil from flowing through the passage past the plungers. Each of the plungers, however, is provided with two portions 65, ltireduced in diameter to permit flow of oil from. one compartment to another. In the normal position of the valve plungers, the upper reduced portions I66 interconnect the high pressure chambers I49 with the ducts I00 and I02, leading to the right side of the intermediate piston 90 and" to the left side of the inner piston 92, respectively, holding the fluid motor in the position shown in Figures 1 and 4. The lower reduced portions I61 on the Valve plungers E35, I36 connect the low pressure compartments I58 with the ducts Illi, I08 leading to the left end of the main cylinder and to the right end of the inner cylinder, respectively. A similar connection is made with the rear pair of valve plungers I31, I 38, associated with the fluid motor (not shown) connected to the other shifting rod I21.

When one of the valve plungers, such as I36 in Figure 8, is depressed to its lower limit of travel, the pressure on the cylinder ducts is reversed. For instance, when the valve plunger I36 is depressed toits lower limit, cylinder duct I00; is disconnected from the high pressure chamber I49 and is connected with the low pressure compartment I58, while cylinder duct I 01 is disconnected from the low pressure compartment I58 and connected with the high pressure compartment I49, thereby shifting the intermediate piston to the right end of its stroke.

The valve plungers I35, I36, I31 and I38 are each provided with a lower end portion I68 of greater diameter than the remainder of the plunger. This portion I68 of the plunger is movable within a lower portion I69 of the vertical cylindrical opening I65 which is enlarged in diameter, and the plunger is urged upwardly by a compression spring E19 until the portion I60 of greater diameter engages the upper end of the enlarged opening: 569, which is, the normal position of the plunger.- Each of the springs I10 reacts against a plug I1I, which is screwed into the lower end of the enlarged opening I69. Each of the plugs I1! has a projection I12 at itsinner end, which extends inside of the spring coil I 10 and is adapted to engage the lower end of the valve plunger to serve as a stop as the plunger moves downwardly, and thus determines the lower limit of, its movement, see Figure 8.

A pair of low pressure compartments I15, I16. are disposed in eachof the outer sections I39, MI of the valve casing and serve to retain any oil that leaks past the valve plungers, returning the oil through upper and lower ducts I11 to the low pressure passage, I55 in the center section I40. An oil seal I19 encircles each of the valve plungers and is set within a recess I19 in the top-of the valve casing.

The lower end of the high pressure distributing passage I46 is drilled to a larger diameter at E80 and contains an excess pressure relief valve in the form of a ball I8I urged against the lower end of the passage M by means of a compression spring I82. The spring reacts against a plug I83 which is threaded into the lower end of the opening I80. A drilled passage I36 connects the chamber I 80 with the low pressure duct I55. The spring I82 is of sufficient strength to hold the ball valve I85 closed under normal operating pressures, but yields to dangerously high pressures and permits the oil from the high pressure duct I46 to escape to the low pressure duct I55.

The lower end of the other high pressure duct I 41 is also drilled to a larger diameter to provide a compartment I85, within which is disposed a valve E86 which seats against the lower end of the passage I I'I, but which can be opened manually to provide a by-pass. The valve I95 is mounted on a valve rod 587, the latter being threaded to engage a bushing I39 which is threaded into the lower end of the compartment I85. By opening the by-pass I85, the gear shifting mechanism is disabled for any purpose such as to permit hand operation. Normally, however, the valve I96 is maintained in closed position. The enlarged portion I35 is connected by the transverse'passage I84 to the low pressure duct The two valve plungers I 35, and I 35, associated with the fluid motor 80, are controlled by a rockable control member I90 comprising a hub I9! rockably journaled on a shaft I92 disposed in a horizontal position between the two valve plungers I35, I 35. Integrally formed with the hub I9I are a pair of oppositely extending presser arms I93, I941 disposed in engagement with the upper ends of the valve plungers I35, 93 5, respectively. When the control member I90 is rocked in one direction, as shown in Figure 8, the end I94 engages the upper end of the valve plunger I39 and depresses the latter, while the other valve plunger I35 is held in normal position by the spring H0, and limited by the enlarged lower portion I68 engaging the upper end of the enlarged opening I69. As stated above, this reverses the oil pressure on the intermediate piston 99 and shifts the latter to right from the position shown in Figure 4 to the position shown in Figure 5. Since the other valve plunger I35 is in neutral position, the pressure remains un changed on the inner piston e2, whereupon the latter remains at the right end of its stroke. By shifting the rockable control member i9 3 back to neutral position, the plunger I 35 is restored to its normal position, thereby restoring the pressure upon the right end of the intermediate piston 90 and returning the latter to the position shown in Figure 4. By rocking the control member I 90 in the opposite direction, the valve plunger I35 can be depressed, thereby reversing the oil pressure on the inner piston 92, shifting the latter to the left from neutral posi tion to position A.

A second rockable control member I90 comprises a hub I9! journaled on the shaft I92 in spaced relation to the hub I9! and is provided with a pair of oppositely extending arm I93, I94 which engage the upper ends of the valve plungers I31, I30, associated with the other gear shiftingfiuid motor (not shown). The opera tion of the second fluid motor is similar to the operation described above in connection with the fluid motor 80. A supporting block I96 is journaled on the shaft I92 between the two control 12 members I90, I90 and is also rockable thereon. A bifurcated control lever I91 has a pair of legs I93, which straddle the block I96 and are pivotally mounted thereon by means of a pivot bolt I99, passing through aligned apertures in the legs iSt and block I96, providing for rocking movement of the lever I91 about the axis of the bolt I99, which is substantially perpendicular to the axis of the shaft I92 and spaced below the latter. A control lever I91 is provided with a pair of oppositely extending dogs 200, 200', which can be shifted into cooperative notches 20I, 20I' in the two control members I90, I00, respectively. Thus, by shifting the control lever I91 to the right as viewed in Figure 6, the dog 200 can be engaged with the notch 20I, and then the lever can be shifted in either direction about the axis of the shaft I92 to rock the control member I90 in either direction to operate the valve plungers I35, I35, selectively. Similarly, the lever I9? can be rocked to the left about the axis of the bolt I 99, to engage the dog 200 with the notch 20I, after which the lever can be shifted about the axis of the shaft I92 to rock the control member I90 for the purpose of depressing either the plungers I3'I' or I38, selectively.

The shaft I92 is journaled in a pair of bearings 2&2 disposed in oposlte ends of a casting indicated generally by reference numeral 203, which is provided with a pair of feet 204 which are rigidly mounted on the top of the center section I 40 of the valve casing I30 and secured thereto by studs 205. The member 203 has a pair of walls 206 extending upwardly from the two bearings 202 and the walls 256 are interconnected by a dome-shaped top portion 207, which is slotted to provide an H-shaped guide for the control lever. The bifurcated portion I91 of the control lever terminates beneath the dome '20! and is slidably received within a tubular member 208 which is disposed in telescopic relation thereto. A handle 209 is fixed to the upper end of the tubular portion 208, and the latter is beveled at 2I0 to provide a conical surface adapted to be received within tapered recesses 2I I disposed in the under side of the dome 207 at the ends of the various branches of the H-shaped slot 2 I2 and at the center of the latter. The conical surface 2I0 is urged into seating engagement with the recesses ZII by means of a compression spring 2I3 disposed within the telescoping members I 91, 208 and adapted to urge the handle 209 upwardly. By first pressing the handle 209 downwardly, the conical portion 2I0 is unseated from the conical recess ZII, after which the handle 209 maybe shifted within the H-shaped slot 2I2, but when the handle 209 is released, the spring 2 I3 forces the conical portion 2!!! upwardly into seating engagement with the recess 2II at that position.

As in the conventional automobile gear shift mechanism, the handle 209 is in neutral position when it is in the center of the H-shaped slot 2I2, as shown in Figure 2, as well as in Figures 6, '7 and 9. The fluid motor is controlled by depressing the handle 209 in theposition shown in Figure 2 and moving it downwardly into the slot at the lower part of Figure 2 after which the handle can be moved to the right or left to depress the valve plungers I36 or I35, selectively. By moving the handle to the upper portion of the H-shaped slot, as viewed in Figure 2, the handle 209 is connected with the other control member I, after which the handle can be moved to the right or left to depress the valve plungers I38 or I31, selectively, to control the fluid motor (not shown), associated with the shifting rod I21.

The third shifting rod I28 in the embodiment shown in Figure 1, is preferably shifted by a suitable manual shifting means to. obtain the first or lowest speed connection of the transmission gears and also the reverse connection. The position indicated at A in Figure 2 corresponds with position A of the gear shift fork I25, which. is the second speed connection. Position B in Figurev -2xcorresponds to position B of the shift fork I25, which is the third speed connection. Positions C and. D correspond: to the positions of the fluid motor which is not shown, associated with shifting rod I2! and provide a fourth and fifth speed connection.

When shifting from one gear connection to another, it is desirable that the transmission be first shifted to neutral before the new gear combination is set up, in order to prevent clashing or stripping of the gears of the transmission. This can, of course, be accomplished by first shifting the handle 2%- to the neutral position N atthe center of the H-slot 2 I2, then actuating the clutch pedal 25, and then shifting the handle 209 to the new position, but it is. preferable that the handle ace be shifted from any position to any other position directly without the intermediate neutral position, in order that the new gear combination be pre-selected before the clutch pedal 25 is actuated. For this purpose, an interlock, indicated by reference numeral 2l 5, is provided between the three shift rods M6, I21, I23. Since interlock mechanisms of this type are known to those skilled in the art, a complete description is not considerednecessary here, but is merely shown in diagrammatic form in Figure l. The mechanism 2-15- comprises apair of vertically disposed interlock bars 2H5, 2H mounted on blocks 2!;8, 2&9, respectively, which are slidable laterally in a groove between guides 22 I preventing movement parallel to the rods. The vertical edges of the bars2 I 6, 2 I l are each beveled and are adapted to fit into V-shaped notches 22!) in each of the rods. I2, iZ'I, I28, which are in alignment with the bars when the latter are in their neutral position. The interlock bars 2 I6, 2H permit only one of the rods to be shifted at a time. As shown in Figure 1, the rod I 28, is in shifted position, with the notch 22! out of engagement with the interlock bar 2H. The edge of" the latter engages the cylindrical surface of the rod I28, forcing the bar 2H into the notch 22 3' in. rod 126', and the block 2.95, fixed to the lower end of bar ZIl' engages block 2I8 to force bar 2H5 into the notch'22'0 in rod I211; Thus, since the blocks are, 2H are prevented from moving longitudinally" of the. rode, the rods. I2! and I25 are prevented from longitudinal shifting movement as long as rod I281 is in a shifted position. When rod' i28 is shifted back to'neutral, its notch 229 is then disposed in alignment with the bar 2H; and permits the latter to move into the notch 22!; in rod I28,.releasing the oppositeedge of the bar 2H from the notch..22li in rod I26. This releases the rod I26 for shifting movement in either direction by the fluid motor 86, since the other interlock bar 2H5 in engagement with the notch. 22!] in rod I2'I, is .re-

leased, from. the notch in rod I25. In this position of the bar ZIS, however, the rod I2! is prevented from longitudinal shifting movement, so that when the handle 209 is shifted from position A or B to position C or D, and the clutch pedal '25 is depressed to initiate a shifting operation, the selector valve I30 is positionedto return the fluid motor to neutral position, but isalso positioned to depress one of the valve plungers I31, I38 and thereby directing oil to the other fluid motor (not shown). The latter, however, is prevented from movement by the bar 2I6 engaging the shift rod I21, therefore the oil flows only to fluid motor 89, shifting the latter to neutral position, but as soon as the latter reaches neutral position, the interlock bar H6 is forced out of engagement with the shift rod t2? and into the notch 22d in rod I26, by forceexerted against the rod I 2? by its associated fluid motor, after which the latter is free to shift its shifting rod I2! to the new gear combination.

The control system described herein relieves the operator from all the effort necessary to shift the gears and actuate the clutch, except for a slight pressure on the clutch pedal which is desirableto. permit him to feel the pressure as the clutch and gears are being actuated. As soon as he removes his foot from the pedal 25, the presure is relieved through the port 59 in the valve casing 65, thereby relieving the pressure from all parts. of the system during normal operation in any gear combination.

During such normal operation, the shift rods I25, I21 and I28 are each held in adjusted position by detent means in the form of a ball 225, which is urged into one of a plurality of grooves 226 in the end of the associated shift rod, by means of a compression spring 22! within a drilled passage 228 in a portion of the transmission housing, indicated diagrammatically at 229.

In order to prevent the gears from being shifted too suddenly and with too much force and thus to prevent gears from being damaged by the hydraulic shifting mechanism, each pair of cylinder ducts is interconected by a spring backed relief valve, which is provided with a spring of sufficient strength that it permits a normal pressure against the gear shifting piston associated therewith, but yields to an oil pressure slightly in excess of the normal, pressure required to shift the gears. Inasmuch as each pair of gears in the, transmission requires a different normal pressure for shifting" the same, separate relief valves are provided for each combination. In Figure 1,

it will beseen that the. cylinder ducts IEO, II at opposite ends of the intermediate piston 98 are interconnected by a passage 23%, within which is disposed a spring check valve 25, which is adapted to yield when the oil pressure in the duct I fit exceeds a normal pressure for shifting the fork I25 from the neutral position N to the position B. It is not necessary to provide a yieldable valve for limiting the oil pressure in cylinder duct I!!!) when the ears are disconnected by shifting the, intermediate piston 952 and thus the shifting fork I25 back to the neutral position. Of course,. the main excess pressure relief valve Ifii stands-ready at all times to. relievethe pressure in the entire. system in caseof any abnormal breakage or jamming. of the mechanism.

In a similar manner, the two cylinder ducts I02, HEB-are. interconnected by a passage 232, Within. which is disposed a spring backed. relief valve fi-tswhich' is adapted to limit the pressure in duct I at during the shifting of the fork I25 to tl-iepositionv A. Separate-valves 23f, 233 are provided for the two different gear combinations, for a greater pressure is required to connect the heavier low speed gears than is required for the lighter high speed gears.

Referring now more particularly to Figure 3 in which the parts are indicated by the same reference numerals of the corresponding parts in Figure 1, to which have been added the suffix a, it will be noted that in this embodiment of the invention, the main supply duct 'lla is not connected to the clutch cylinder 35a, but is connected with the high pressure chamber 51a to receive oil directly therefrom, but through a valve port 235 which is interposed between the high pressure chamber 61a and the supply duct Ha. A poppet valve 236 is normally held in closed position in the port 235 by means of a compression spring 231, which opposes the pressure of the oil within the chamber 61a. The spring 237 is sufficiently strong to hold the valve 236 closed against the pressure required in the chamber 61a to actuate the clutch operating cylinder 35, but when the piston reaches the end of its stroke in the cylinder 36a, the pressure immediately increases and unseats the valve 236 against the pressure of the spring 237, thereby allowing the oil to flow through the supply duct 11a to the selector valve I30. The valve 236 insures that the clutch has been completely released before the oil pressure is supplied to the gear shifting cylinders.

I do not intend my invention to be limited to the exact details shown and described herein except as set forth in the claims which follow.

I claim:

1. Selector valve control means, comprising: a support having a pair of upstanding spaced apart ears apertured in alignment to provide a pair of coaxial mounting members; a shaft carried at its opposite ends in said members; a pair of rocker arms spaced apart axially on the shaft and rockably carried by the shaft between said members; means on each arm providing an upstanding notched lug, said lugs being aligned with respect to a plane passed through and including the shaft axis; a lever base member carried by the shaft between the spaced apart rocker arms for rocking about the shaft axis; means on said lever base member providing a pivot axis normal to the shaft axis and centrally between the rocker arms; a lever handle member normally upstanding from the base member in a central position and connected thereto on said last named pivot axis for rocking of said handle member and base member together in a plane normal to and about the shaft axis and for rocking of the handle member with respect to said base member in a plane axially of said shaft; and a pair of projections on the lever handle mem ber, one at each side thereof, extending in opposite directions axially of the shaft respectively toward the notched lugs on the rocker arms and disengaged from said lugs when the lever handle member is in its normal central position but selectively engageable with said lugs when the lever handle member is rocked as aforesaid with respect to the lever base member.

2. Selector valve control means, comprising: a support having a pair of upstanding spaced apart ears apertured in alignment to provide a pair of coaxial mounting members; a shaft carried at its opposite ends in said members; a pair of rocker arms spaced apart axially on the shaft and rockably carried by the shaft between said members; means on each arm providing an upstanding notched lug, said lugs being aligned with respect to a plane passed through and in- 16 cluding the shaft axis; a lever base member 'carried by the shaft between the spaced apart rocker arms for rocking about the shaft axis; means on said lever base member providing a pivot axis normal to the shaft axis and centrally between the rocker arms; lever handle member normally upstanding from the base member in central position and including upper and lower vertically telescopic parts, the lower part of which is connected to the base member on said last named pivot axis for rocking of said handle member and base member together in a plane normal to and about the shaft axis and for rocking of the handle member with respect to said base member in a plane axially of said shaft; a pair of projections on the lever handle member, one at each side thereof, extending in opposite direc tions axially of the shaft respectively toward the notched lugs on the rocker arms and disengaged from said lugs when the lever handle member is in its normal central position but selectively engageable with said lugs when the lever handle member is rocked as aforesaid with respect to the lever base member; a plate-like element carried rigidly on the aforesaid ears and extending in a plane generally normal to the principal axis of the lever handle member and formed with slots in accordance with the rocking movement of said handle member both with and with respect to the lever base member, said plate having a portion defining a central position for the lever handle member; spring means extensible between the upper and lower handle parts for resiliently urging the upper handle part upwardly; and means on said upper handle part engaging the plate-like element for retaining the handle member in selected positions in the aforesaid slots, said last named means being also engageable with the aforesaid plate portion for retaining the handle member in its central position.

EMIL F. JIRSA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 954,492 Zelle Apr. 12, 1910 1,805,120 Von Erhardt May 12, 1931 1,823,590 Christensen Sept. 15, 1931 1,845,797 Kearney Feb. 16, 1932 1,876,249 Krenzke Sept. 6, 1932 1,991,124 Sharpe Feb. 12, 1935 2,043,314 Wemp June 9, 1936 2,075,917 Vorech Apr. 6, 1937 2,079,684 Church May 11, 1937 2,181,532 Hill et al Nov. 8, 1939 2,220,673 Bloomheart Nov. 5, 1940 2,251,293 Schwartz Aug. 5, 1941 2,265,260 Argo Dec. 9, 1941 2,277,454 Porsche Mar. 24, 1912 2,328,849 Schoelm Sept. 7, 1943 2,329,742 Bush Sept. 21, 1943 2,336,715 C'asler Dec. 14, 1943 2,345,224 Upp Mai. 28, 1944 FOREIGN PATENTS Number Country Date 140,336 Great Britain Mar. 25, 1920 

